Nitrogen supply is one of the most important growth-regulating factors in ecosystems. Anthropogenic emissions and other human activities are changing local, regional and global nitrogen cycles. The author discusses how land ecosystems with their organisms, plants, animals and microorganisms are affected by changes in nitrogen supply and how organisms influence nitrogen cycling in natural and polluted ecosystems.

Inhalt
1 Introduction: Geochemical Occurrence of Nitrogen. Natural Nitrogen Cycling and Anthropogenic Nitrogen Emissions.- 2 Nitrogen in Plants and Soils: Physiological and Microbiological Background for Biological Nitrogen Turnover.- 2.1 Nitrogen in Plants.- 2.2 Nitrogen in Soils: Transformations, Uptake, Losses.- 2.3 Nitrogen and Transport Mechanisms in Terrestrial Ecosystems.- 3 Nitrogen-Limited and Nitrogen-Depleted Terrestrial Ecosystems: Ecological Characteristics.- 3.1 Definitions.- 3.2 Nitrogen in Forest Successions.- 3.3 Biological Control of Nitrogen Cycling.- 3.4 Nitrogen Depletion by Fire and Other Disturbances.- 3.5 Nitrogen Depletion by Removal of Biomass or Litter.- 3.6 Concluding Remarks.- 4 Nitrogen-Enriched and Nitrogen-Saturated Ecosystems.- 4.1 Definitions.- 4.2 Sites Naturally Enriched with Nitrogen.- 4.3 Nitrogen Enrichment by Preindustrial Agricultural and Pastural Land Use.- 4.4 Enrichment by Chemical Fertilizers and Urban Waste Products.- 4.5 Enrichment by Atmospheric Emissions from Modern Industrial and Agricultural Activities.- 5 Consequences of Increased Nitrogen Supply to Forests and Other Natural and Seminatural Terrestrial Ecosystems.- 5.1 Changes in Vegetation and Fauna.- 5.2 Soil Chemical and Biological Changes, Including Nitrogen Losses to Groundwater and Atmosphere.- 5.3 Acute Damage to Plants Associated with Emissions of Nitrogen Compounds.- 5.4 Interactions Between Effects of Anthropogenic Nitrogen Emissions and Other Human Impacts on Terrestrial Ecosystems.- 6 Conclusions.- References.